Athens dock workers protest after 8 killed in ship explosion

At least eight people have been killed by a gas explosion aboard a tanker undergoing repairs in a dockyard near Athens, sparking violent demonstrations by dock-workers over safety standards.

Workers clashed with riot police outside Greece's Merchant Marine Ministry in a protest at what they say are regular violations of safety procedures at the state-run Perama dockyard west of Athens.

They have called a three-day strike.

Merchant Marine Minister George Voulgarakis says an investigation into the cause of the accident is underway and two people responsible for safety issues have been arrested.

Rescue crews were searching the Panamanian-flagged Friendship Gas tanker for more missing after the blast late on Thursday (local time) caused by workers using acetylene torches.

It was unclear whether any more workers were killed by the explosion.

"We don't know exactly how many are missing because records of how many people were working were not kept and they seem to have been either unregistered or illegal workers," a police official, who declined to be named, said.

At least four people were taken to hospital with injuries after the fire.

In July 2007, two workers were killed in a similar incident in Perama.

A statement by the umbrella public sector workers union said that lack of safety measures and the impunity of shipowners had turned dockyards into a "permanent deathtrap for workers".

Greece has the world's largest merchant marine fleet and Greek-run companies control nearly a fifth of the world's shipping fleet.